ACES  LIBRARY 


UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.  203 


SEED  PRODUCTION  IN  APPLES 


By  CHARLES  S.  CRANDALL 


URBANA,  ILLINOIS,  AUGUST,  1917 


Summary  of  Bulletin  No.  203 

1.  In  this  bulletin  is  recorded  the  seed  production  of  four  groups  of  apples, 
a  total  of  31,972  fruits:  large  apples  of  orchard  varieties,  12,912;  small  apples  of 
orchard  varieties,  8,500;  crabs,  0,642;  and  hand-pollinated  fruits,  3.918. 

2.  Seed  production  in  large  apples  exceeded  that  in  small  apples  by  14.7 
percent,  and  was  nearly  twice  that  recorded  for  crab  fruits;  the  average  seed  pro- 
duction was,  for  large  apples,  8.27;  for  small  apple?,  7.21;  and  for  crab  fruits, 
4.22.  Page  188 

3.  The  minimum  average  seed  content  was  2.8,  found  in  small  fruits  of 
Collins;  the  maximum  average  was  15.04,  found  in  large  fruits  of  Shockley. 

Page  188 

4.  Approximately  12  percent  of  the  large  fruits  of  orchard  varieties  contained 
the  assumed  normal  of  10  seeds;  69  percent  averaged  below  this  normal,  and 
about  18  percent  above  normal.  Page  189 

5.  There  was  considerable  variation  in  number  of  carpels;  four  orchard 
varieties  held  to  the  normal  of  five;  all  others  showed  departures  from  this  normal. 
The  range  for  large  fruits  was  4  to  8;  for  small  fruits,  2  to  8.  Page  191 

6.  Parthenocarpic  fruits  were  found  more  often  among  small  fruits  than 
among  large  fruits  of  orchard  varieties.  Page  190 

7.  Percentages  of  ovules  that  developed  as  seeds  were  higher  for  groups 
of  large  apples  than  for  small  apples  in  twenty  out  of  twenty-one  varieties 
examined.  Page  198 

8.  A  test  of  extremes  in  size  for  one  variety  confirmed  results  from  all 
varieties  and  strengthened  the  evidence  that  large  apples  develop  a  larger  pro- 
portion of  the  ovules  they  contain  than  do  small  apples.  Page  199 

9.  Crab  fruits  ranged  in  numbers  of  carpels  from  2  to  12  and  had  a  seed 
range  of  0  to  14.  Pages  205,  207 

10.  Production  of  ovules  in  excess  of  the  expected  normal  occurred  more 
frequently  among  orchard  varieties  than  among  crabs.  Page  211 

11,  Control  of  pollination  exercised  no  marked  influence  on  numbers  of  seeds 
developed.  Page  213 


SEED  PRODUCTION  IN  APPLES 

By  CHAELES  S.  CR  AND  ALL,  Chief  in  Plant  Breeding  in  Horticulture 

INTRODUCTION 

Each  normal  fruit  of  the  common  apple  is  made  up  of  five  centrally 
located  carpels,  each  carpel  forming  one  cell.  Each  of  the  five  cells 
contains  two  ovules  attached  near  the  base  to  the  perpendicular 
placenta,  which  is  on  the  inner  side  of  the  cell,  and  hence  central  in 
the  fruit.  When  all  ovules  are  fertilized  and  develop  into  seeds,  the 
full  complement  is  ten  for  each  normal  apple. 

Examination  of  a  considerable  number  of  apples  brings  *out  the 
fact  that  departures  from  the  normal  number  of  seeds  are  common 
and  of  all  degrees,  from  an  entire  absence  of  developed  seeds  to  an 
increase  to  more  than  two  and  one-half  times  the  normal.  Naturally 
these  variations  in  the  performance  of  individuals  and  varieties  in 
the  matter  of  seed  production  suggest  questions  regarding  the  factors 
governing  fertilization  and  seed  development,  the  relation  of  seed  for- 
mation to  size  of  fruit,  and  the  possibility  of  developing  a  definite 
system  of  association  of  orchard  varieties  that  would  make  for  increase 
in  fruit  production.  The  development  of  such  a  system  could  not 
be  accomplished  in  one  year,  nor  in  several  years;  it  would  require 
long  and  patient  effort,  but  there  can  be  no  doubt  that  valuable  scien- 
tific as  well  as  economic  results  would  attend  its  successful  accomplish- 
ment. It  is  not  the  intention  to  enlarge  upon  this  idea  in  the  present 
publication,  but  simply  to  place  on  record  observations  that  have 
been  made  relative  to  the  actual  seed  production  of  groups  of  apple 
varieties  grown  under  usual  orchard  conditions. 

As  a  first  step  in  a  study  of  seed  production  in  apples  it  is  desirable 
to  know  something  of  the  behavior  of  common  orchard  varieties  in 
this  regard.  Do  they  live  up  to  the  possibilities  in  the  matter  of 
seed  production  ?  Do  they  fall  short  of,  or  do  they  exceed  a  definite 
normal?  Are  there  well-defined  differences  in  seed  production  that 
may  rank  as  varietal  characteristics?  How  do  varieties  producing 
very  large  fruits,  Wolf  River  for  example,  compare  in  seed  production 
with  varieties  producing  small  fruits,  such  as  Red  June  or  Lady? 
Within  a  variety,  does  any  definite  relation  exist  between  size  of 
fruit  and  seed  content?  These  are  some  of  the  questions  that  are 
suggested  at  the  outset  of  the  inquiry. 

OPINIONS  REGARDING  SEED  PRODUCTION 

Horticultural  literature,  so  far  as  consulted,  yields  little  infor- 
mation concerning  the  questions  here  suggested.  Seed  production 
in  apples  appears  to  have  been  passed  over.     There  are  no  records 

185 


186  Bulletin  No.  203  [August, 

of  extended  investigation  and  only  meager  references  to  the  perform- 
ance of  this  fruit  in  this  particular.  There  do  appear  certain  state- 
ments indicating  common  belief  in  a  general  principle  that  with 
seed-bearing  plants,  and  especially  with  economic  fruit  plants,  in 
which  there  is  large  development  of  edible  parts,  there  is  a  correspond- 
ing diminution  in  seed-producing  capacity;  or,  to  state  it  more 
definitely,  fruits  with  highly  developed  fleshy  parts  produce  fewer 
seeds  than  do  those  fruits  in  which  the  fleshy  parts  are  not  enlarged. 

The  development  of  seeds,  the  forming  of  the  embryos,  and  the 
storing  of  food  necessary  for  the  young  plants  form  an  exhaustive 
process  drawing  heavily  upon  the  resources  of  the  plant.  It  is  a  per- 
fectly natural  conclusion  that  the  production  of  full  complements  of 
seeds  and  the  storing  of  large  quantities  of  edible  fruit  flesh  are 
antagonistic  and  that  large  size  and  full  seed  production  are  not  likely 
to  be  at  a  maximum  in  the  same  fruits. 

In  discussing  compensation  and  economy  of  growth,  Darwin1  makes 

this  general  statement: 

1 '  When  the  seeds  in  our  fruits  become  atrophied,  the  fruit  itself  gains  largely 
in  size  and  quality. " 

Lindley  says2 : 

' '  Sterility  is  a  common  malady  of  cultivated  plants,  the  finer  varieties  of  fruit, 
and  all  double  and  highly  cultivated  flowers,  being  more  frequently  barren  than 
fertile.  This  arises  from  several  causes.  The  most  common  cause  of  sterility  is 
an  unnatural  development  of  some  organ  in  the  vicinity  of  the  seed,  which  attracts 
to  itself  the  organizable  matter  that  would  otherwise  be  applicable  to  the  support 
of  the  seed.  Of  this  the  Pear,  the  Pineapple,  and  the  Plantain  are  illustrative 
instances. ' ' 

E.  L.  Sturtevant3  affirms  that  small  fruits  contain  more  developed 
seeds  than  do  large  fruits.    He  writes  as  follows: 

''The  better  varieties  of  the  apple  usually  contain  some  abortive  seeds  and 
are  sometimes  individually  to  be  found  seedless.  As  a  rule,  where  there  is  a 
tendency  to  abortive  seeds,  the  larger  and  finer  the  apple  the  greater  the  number 
of  abortive  seeds.  Thus  five  Baldwin  apples,  weighing  thirty  ounces,  had  eleven 
plump  and  nine  shriveled  seeds;  five  others  from  the  same  barrel,  and  weighing 
seventeen  ounces,  furnished  twenty-five  plump  and  three  abortive  seeds." 

Dr.  Sturtevant 's  conclusion  appears  to  be  based  upon  examination 
of  145  apples  representing  thirty-five  varieties.  One  variety,  the  Bald- 
win, was  represented  by  sixty-seven  apples;  of  the  others,  eighteen 
had  one  fruit  each,  four  had  two  each,  and  twelve  had  numbers  of 
fruits  from  three  to  eight.  The  average  number  of  good  seeds  was 
5.67;  the  minimum  number  found  was  one  each  in  Newtown  Pippin 
and  Gray  Russet;  the  maximum  was  12.75  in  Northern  Spy.  The 
numbers  of  fruits  examined,  however,  were  too  small,  at  least  for  all 
varieties  except  Baldwin,  to  serve  as  a  good  index  of  the  seed-producing 
capacities  of  the  varieties. 


Origin  of  Species,  6th  ed.,  p.  139. 

2Theory  of  Horticulture,  Downing,  2d.  ed.  (1852),  p.  170. 

"On  Seedless  Fruits,  Mem.  Torrey  Bot.  Club,  1,  No.  4  (1890),  p.  145. 


1917]  Seed  Production  in  Apples  187 

The  authors  quoted  do  not  state  the  converse  of  the  principle  laid 
down,  but  each  leaves  the  reader  to  infer  that  fruits  not  highly  devel- 
oped, those  in  or  near  the  wild  state,  while  deficient  in  flesh,  the  part 
valuable  to  man,  excel  in  seed  production. 

Bailey1  expresses  a  view  contrary  to  that  given  by  the  writers 
quoted  above.    He  says : 

"As  a  rule,  the  cultivated  varieties  of  apples  contaiu  more  seeds  than  the 
wild  apples  of  Europe  do.  Forty  specimens  of  the  wild  crab  (Pyrus  Malus)  of 
central  Europe  produced  an  aggregate  of  two  hundred  fifty-six  seeds,  or  an 
average  of  six  and  two-fifths  seeds  to  each  fruit.  Forty  Northern  Spys  contained 
four  hundred  eighty-one  seeds,  or  an  average  of  twelve  and  one-fortieth  to  the 
fruit.  Normally,  the  apple  should  contain  ten  seeds,  two  to  each  carpel,  but  some 
of  these  Spys  had  fifteen  seeds  and  one  had  eighteen.  Yet  some  other  varieties 
of  apples  contain  fewer  than  the  normal  number,  while  some  are  almost  entirely 
seedless.  There  is  generally  a  slight  increase  in  seed  production  as  fruits  develop 
away  from  the  first  type,  especially  if  the  fruits  become  larger.  This  is  a  natural 
consequence  of  the  increase  in  size,  tho  it  bears  no  constant  ratio  to  this  increase. " 

SEED-PRODUCTION  RECORDS 

As  a  basis  from  which  to  judge  the  performance  of  apples  and 
crabs  in  seed  production  when  varieties  are  grown  in  mixed  plantations 
and  left  open  for  undisturbed  visitation  by  insects,  records  were  taken 
from  28,054  individual  apples.  Thirty-two  orchard  varieties  were 
represented  by  21,412  fruits,  and  twenty-five  species  and  varieties  of 
the  genus  Malus  were  represented  by  6,642  fruits.  This  latter  is  a 
strictly  crab  group ;  none  of  the  species  or  varieties  have  any  economic 
value  other  than  as  ornamentals.  They  vary  widely  among  themselves 
and  represent  several  types,  but  all  closely  approximate  the  wild 
originals. 

With  the  exception  of  Garfield  and  Twenty  Ounce,  varieties  repre- 
sented by  small  numbers  of  fruits  very  uniform  in  size,  the  fruits  of 
each  orchard  variety  were  divided  into  two  groups  on  the  basis  of  size, 
a  group  of  large  apples  and  a  group  of  small  apples,  in  order  to 
determine  whether  or  not  there  is  constant  difference  in  seed  produc- 
tion between  groups  thus  separated.  Transverse  diameter  was  taken 
as  the  basis  of  division.  In  a  few  varieties  all  fruits  65  mm.  or  above 
in  diameter  were  classed  as  large,  all  below  that  dimension  as  small. 
In  most  varieties,  however,  it  was  possible  to  leave  a  gap  of  from 
3  to  10  mm.  between  groups  and  in  that  way  make  them  more  distinct ; 
thus,  in  several  varieties  the  maximum  for  the  group  of  small  apples 
was  70  mm.,  and  the  minimum  for  the  group  of  large  apples,  75  mm. 

In  the  crab  group  there  prevailed  such  uniformity  in  the  size  of 
fruit  within  each  species  or  variety  that  no  division  into  size-groups 
was  attempted. 

Records  obtained  from  the  fruits  examined  support  the  view  that 
the  more  highly  developed  fruits,  that  is  to  say,  such  fruits  as  are 

^he  Survival  of  the  Unlike  (1901),  p.  253. 


188  Bulletin  No.  203  [August, 

produced  by  varieties  commonly  grown  in  orchards,  develop  seeds  in 
greater  numbers  than  do  the  crab-like  fruits  of  less  highly  developed 
forms  of  the  genus  Mains.  A  further  fact  developed  from  the  records 
was  that  in  nearly  all  the  varieties,  the  fruits  of  which  were  divided 
into  size-groups,  the  groups  containing  large  apples  produced  more 
seeds  than  did  the  groups  containing  small  apples.  The  differences 
between  these  three  classes  of  fruits  in  average  seed  production  are  as 
follows : 

1.  Average  seeds  to, the  fruit  for  12,912  apples  of  large  size,  representing 

thirty-two  varieties,  8.27. 

2.  Average  seeds  to  the  fruit  for  8,500  apples  of  small  size,  representing 

thirty  varieties,  7.21. 

3.  Average  seeds  to  the  fruit  for  6,642  apples,  representing  twenty-five  crab- 

like forms  of  Malus,  4.22. 

Here  the  average  for  large  orchard  fruits  exceeds  the  average  for 
small  orchard  fruits  by  14.7  percent,  and  is  very  nearly  twice  as 
great  as  for  the  crab-like  forms. 

In  each  of  the  three  groups  for  which  average  seed  production  is 
given  there  was  a  wide  range  between  maximum  and  minimum  seed 
production  as  exhibited  by  the  different  varieties  and  species.  Thus, 
among  the  groups  of  large  fruits,  Collins  was  the  least  productive, 
the  average  for  261  fruits  being  4.09  seeds,  and  Shockley  the  most 
productive,  with  an  average  for  177  fruits  of  15.04  seeds.  In  the 
groups  of  small  fruits,  Collins  was  again  the  least  productive,  with 
an  average  for  150  apples  of  2.8  seeds :  the  maximum  here,  as  in  the 
groups  of  large  fruits,  falls  to  Shockley,  which,  for  177  apples,  had 
an  average  of  14.59  seeds. 

In  the  crab  group  the  lowest  in  seed  production  was  Malus  fusca, 
with  an  average  of  1.32  seeds  to  each  fruit,  but  this  species  was  repre- 
sented by  so  few  fruits  that  this  average  is  not  regarded  as  depend- 
able for  the  species.  The  next  lowest  was  Malus  atrosan guinea,  which, 
for  the  100  fruits  examined,  had  an  average  of  2.02  seeds  to  each  fruit. 
The  most  productive  in  this  group  was  Malus  Malus  flore  pleno,  which, 
for  100  fruits,  had  an  average  of  7.8  seeds  to  each  fruit.  The  second 
in  seed  production  was  Malus  microcarpa,  which,  for  100  fruits,  had 
an  average  of  7.09  seeds  to  each  fruit. 

Between  the  extremes  in  seed  production  given  for  the  different 
classes  of  fruits  the  averages  were  various:  no  two  were  alike,  but 
the  majority  tended  towards  approximation  of  the  general  average 
for  the  class.  High  seed  production  appeared  to  be  characteristic  of 
some  orchard  varieties,  while  certain  others  of  these  varieties  were 
equally  constant  in  low  production.  Some  varieties  tended  to  con- 
centrate within  the  normal  of  ten  seeds,  as  was  the  case  with  Arkansas 
Black,  Grimes,  Fameuse,  and  Rome;  others  tended  to  scatter 
the  production  over  a  wide  range,  as  1  to  27  in  Shockley,  3  to  21  in 
Rhenish  May,  and  3  to  19  in  Winter  Rambo.    In  the  groups  of  apples 


ber  of  seeds  per  fruit 


14   15  |  16  |  17  |  18  |  19  |  20  |  21   22   23  |  24 


2 


3   2 

1 


1 
13 

205 


5 

198 


15   12 


6   1 

145  j  103 

17   16 


3 

29 


21   4 
5   7 


14 


Table  1. — Seed  Production  in  Orchard  Varieties: 

Large  Fruits 

No.  of 

Average 

AV(mmT' 

Distribution  of 

A7^f 

Distribution  of  fruits  as  to 

number  of  seeds  per  fruit 

\  anetv 

Long 

1  Trana- 

1  ve-ie 

I          .-,'617 

1   8 

5    |    6 

'' 

8    |    9    |  10 

11       12 

isfa 

15 

16 

17       IS 

10      20 

25      21 

Ark:us;i.s  Hl.ick 

200 
1393 
261 

200 

200 

200 
200 
374 
200 

200 
200 
863 
200 

2  398 

177 
328 
200 

166 
513 

1190 
550 

200 

200 

14-1  L'li 

1 75  20 
57.83 

115.66 

17S.r,9 

2011  11 

12lj)5 

120.76 
112.26 
141.18 
141.46 
151.95 

128.00 
154.93 
170.85 
105.17 
116.80 

107.10 

126.72 
2.1.1.70 
125.58 
121.16 

197.31 
132.10 

119.06 
106.09 
135.51 

207.94 

116216 

63.67 
58.84 
57.90 
41.72 

55.13 
68.22 
65.41 

67.01 
52.85 

50.32 
55.96 
60.39 
60.31 
57.88 

55.86 

57^29 

61.26 

50.80 
52.41 
68.64 
53.83 
59.04 

57^25 
54.10 

54^0 

74.16 
70.99 
74.00 
48.66 

66.33 
74.04 

199 

1392 

2       259 

11       189 

200 

4        96 

2 
80 

21 

117 

29 

110 

2 

3 
36 

9.23 
5.97 
4.09 
5.97 

9^8 

9.44 
7.10 
5.96 

7.97 
7.15 
5.90 
5.77 
5.18 

8.13 
7.00 
1           4.28 
9.33 
10.37 

11.65 
7.40 

8.'l4 

5.94 
8.30 

1  8.11 
8.60 

4  '         9.98 

9.11 
9.74 

1 
4|    12 
3j    16 

2 

4 

38 
45 

1 

1 
32 

17 

26 
46 

5 
49 

14 
23 

38 
7 

11 

-6 
41 

106 
26 
29 
74 
35 

27 

71 

132 
43 

5 

56 
43 

28 

24 
46 
44 

12 

56 

11 
23 

13 

122 
41 
24 

50 

36 

18 

202 
45 

82 

38 

21 

112 

71 

41 

77 
5 
6 

13 

52 
49 

132 

18 

21 

11 
51 
32 

215 
24 

4 
66 
50 

10 
173 

676 

r,r, 

47 

20 
29 

7 
20 
52 

2 

100 
12 

29 

57 
40 

40 
39 

7 
108 
19 

525 
94 

38 

22J12 

sj     6 

2 

2 

39      85 

is       11 

152 

42 

1 

2 
70 

2 

2 

8 

12 
25 

45 
4 
4 

2 

12 

22 
4 

1 
1 

2        1 

67.02  1         1     292 

s;  is 

67.66 
64.59 

70231 
71.61 

69.25 
75.49 
73.31 
63.64 
67.54 

63.01 

649 

1    200 

.  18  ~  ~ 

2        9 

198 
12 

9 

7 

2 

2 
20      55 

1 
I         1 

11 
9 
4 

1 

17      29 

33      46 

2l 

28:    33 

Mammoth  Blark  T«  i u' , 
McClellan 

6 

199 

199 

837 
199 
198 

2  276 

1118 

43 
34 

2 

42 
17 

8 

5 

18 
13 
10 
5 

14 
26 
113 

8 

83 

24 

44 
17 

29 

23 
27 

1 

m  13 

301  205 
16    15 

3J     29 
6J       2 

: 

7 

' 

99    143  '  145 

14     10 
27     16 

249  222 
4       2 
10       9 

13|      5 

2       3 

1 

43|    15 
66     46 

17     11 

Polische  Jungfrau 

16 

1        1 

5 

1         2 

5     18 

2 

27 
9 

7 

■!, 
3 
7 

6 

115 

17 

14 

1 
103 
16 

7 

31 

12 
4 

4 

Smith  Cider 

Tolman 

Twenty  Ounce 

66.40  ! 
69.00 

78.90 

324 
165 

65.70                 117 
61.42  !      2    1 185 

68.72          1       391 

■ 

Winter  Rambo 

Wythe 

51.19       67.81   '      l'     198 

i        0 

12012 

as  to  number  of  seeds  per  fruit 

|  13'  |  14  |  15  |  16   |  17  |  18  |   19 

|  20 

1  21 

22 

23   |  24  |  25 

26  |  27 

1 

3 

2 

1 

i 

1 

1 

1 

o 

♦ 

5 

6 

3       1 

1 

21 

15 

11       3 

3 

3 

12 

10 

21      16 

16 

13 

11 

14 

9 

1 

2 

1 

2 

1 

2 

1 

12 

4 

4        1 

1 

3 

3 

2        3 

5 

5 

o 

1917]  Seed  Production  in  Apples  189 

of  large  size,  no  fruits  had  less  than  four  seeds  in  Garfield,  Osceola, 
Polische  Jungfrau,  and  Wythe ;  none  had  less  than  three  in  Crawford, 
Rhenish  May,  Smith  Cider,  Willow,  Winesap,  and  Winter  Rambo. 

Seedless  apples  occurred  in  the  large  size-groups  of  McMahon  and 
Twenty  Ounce,  in  both  size-groups  of  Ben  Davis,  Collins,  Golden  Ball, 
Minkler,  and  Wealthy,  and  in  the  small  size-groups  of  Bailey  Sweet, 
Indian,  Jonathan,  Isham,  Osceola,  Rhenish  May,  Shockley,  Tolman, 
and  Winesap ;  they  occurred  rather  more  frequently  among  small 
apples  than  among  large.  Seedless  apples  will  be  referred  to  again  in 
connection  with  detailed  accounts  of  the  several  classes  of  fruits. 


ORCHARD  VARIETIES 

Records  of  numbers  of  carpels  and  distribution  of  seeds  for  the 
two  size-groups  of  orchard  varieties  are  brought  together  in  tabular 
form  in  Tables  1  and  2.  Records  of  ovule  production  of  the  orchard 
varieties  are  presented  in  Table  7. 

Distribution  of  seed  production  in  its  relation  to  the  full  normal 
content  of  ten  seeds  is  of  interest  as  showing  the  extent  of  departures 
from  the  normal  in  both  directions.  Considering  the  apples  according 
to  the  classes  into  which  they  have  been  divided,  the  apples  of  large 
size  as  produced  by  orchard  varieties  may  come  first. 

Seed  Distribution  of  Apples  of  Large  Size 

The  apples  of  large  size  included  thirty-two  varietal  groups,  aggre- 
gating 12,912  apples ;  they  produced  106,845  seeds,  an  average  of  8.27 
seeds  to  each  fruit.  The  number  of  apples  producing  the  normal  of 
ten  seeds  was  1,610,  or  12.5  percent  of  the  whole  number.  These 
apples  bore  16,100  seeds,  or  approximately  15  percent  of  the  number 
of  seeds  produced  by  all  fruits  of  the  group.  The  number  of  apples 
falling  below  normal  in  seed  production  was  8,913,  or  69  percent  of 
the  total ;  these  apples  bore  58,412  seeds,  or  54.67  percent  of  the  total 
produced  by  fruits  of  this  class.  With  seed  production  above  normal 
there  remained  2,389  apples,  or  18.5  percent  of  the  total ;  these  bore 
32,333  seeds,  or  30.26  percent  of  the  total  seeds. 

Seed  Distribution  of  Apples  of  Small  Size 

The  groups  of  small  apples  represented  thirty  varieties,  and  to- 
gether contained  8,500  apples  which  produced  61,325  seeds,  an  average 
of  7.21  to  each  fruit.  The  number  of  apples  producing  the  normal  of 
ten  seeds  was  1,020,  or  12  percent  of  the  total;  these  produced  10,200 
seeds,  or  16.63  percent  of  the  total.  The  number  of  apples  producing 
less  than  ten  seeds  was  6,786,  or  79.84  percent  of  the  total;  these 
produced  42,178  seeds,  or  68.78  percent  of  the  seeds  produced  by  the 


190  Bulletin  No.  203  [August, 

group.  The  number  of  apples  with  seeds  ranging  above  ten  was  694, 
or  8.16  percent:  these  produced  8,947  seeds,  or  14.59  percent  of  the 
seed  total. 

Comparison  of  Seed  Distribution  of  the  Two  Size-groups 

Comparing  the  size-groups,  it  is  seen  that  the  percentages  of  fruits 
having  the  normal  number  of  ten  seeds  were  nearly  the  same,  12.5 
percent  for  the  large  and  12  percent  for  the  small.  In  numbers  of 
fruits  having  seeds  in  excess  of  ten  the  large  fruits  lead  by  a  consider- 
able margin ;  the  percentages  were  18.5  for  large  and  8.16  for  small. 
Of  fruits  with  less  than  the  normal  number  of  seeds,  small  fruits  had 
the  greatest  numbers,  nearly  80  percent  as  compared  with  69  percent 
for  large  fruits.  Seedless  fruits  numbered  37  among  large  apples  and 
64  among  small  apples.  Apples  having  one  seed  each  numbered  93 
for  the  groups  of  large  apples  and  121  for  the  groups  of  small  apples. 
With  two  seeds  each  there  were  231  large  apples  and  277  small  apples ; 
from  this  there  was  a  gradual  increase  in  number  of  apples  with 
each  addition  to  the  seeds  to  each  fruit,  until  the  maximum  of  1,843 
apples  of  large  size  and  1,257  apples  of  small  size  was  reached 
with  nine  seeds  to  each  fruit.  Above  this  the  decline  in  numbers 
was  rapid  for  both  classes,  but  there  were  still  a  considerable  number 
of  apples  having  large  excess  in  numbers  of  seeds.  Thus,  95  large 
apples  had  eighteen  seeds  each,  48  had  nineteen  each,  and  36  had 
twenty  or  above.  Among  small  apples,  16  had  eighteen  seeds  each, 
11  had  nineteen  each,  and  27  had  twenty  or  above. 

Number  and  Distribution  of  Carpels 

The  number  of  carpels  in  a  normal  apple  is  five,  but  just  as  there 
are  more  or  less  frequent  abnormalities  in  number  of  floral  parts, 
sepals,  petals,  and  stamens,  so  there  are  departures  from  the  normal 
in  number  of  cells  in  the  compound  ovary.  Among  fruits  of  orchard 
varieties  examined  there  were  found  789  apples,  or  3.68  percent  of  the 
total  number,  that  departed  from  the  normal  in  number  of  cells.  In- 
crease in  number  was  much  more  frequent  than  diminution ;  129  fruits 
had  less  than  five  cells  and  660  had  more  than  five. 

Distribution  of  the  abnormalities  among  varieties  was  not  at  all 
uniform.  Winter  Eambo  had  more  than  any  other  variety,  243  out 
of  1,050  apples,  or  23.14  percent:  1  fruit  had  four  cells,  186  had  six 
cells,  50  had  seven  cells,  and  6  had  eight  cells,  while  807  were  normal 
with  five  cells  each.  Rhenish  May  had  the  next  largest  number  of 
fruits  showing  departures  from  normal,  219,  but  because  of  the  larger 
number  of  apples  examined  the  percentage  was  only  6.42,  much  lower 
than  for  Winter  Rambo.  In  this  variety  .there  were  8  fruits  with 
three  cells  each,  50  with  four  cells,  160  with  six  cells,  and  1  with  seven 


1917]  Seed  Production  in  Apples  191 

cells.  Huntsman  had  the  third  largest  number  of  abnormalities,  with 
130  six-celled  fruits  and  2  having  seven  cells  each.  This  variety  was 
represented  by  1,261  apples,  and  the  percentage  of  departures  from 
normal  was  10.46.  Numbers  of  fruits  with  other  than  normal  cells 
were  very  much  smaller  for  the  remaining  twenty-five  varieties  among 
which  they  were  distributed.  Five  of  these  varieties,  Bailey  Sweet, 
Grimes,  Osceola,  Twenty  Ounce,  and  Wolf  River,  with  an  aggregate  of 
1.911  apples,  had  each  one  six-celled  fruit,  all  others  being  five-celled. 
Four  varieties,  Indian,  Isham,  Jonathan,  and  Shockley,  with  a  total 
of  1,606  apples,  had  only  five-celled  fruits. 

As  between  the  two  size-groups,  large  and  small,  there  was  very 
little  difference  in  the  frequency  with  which  abnormalities  in  cells 
appeared.  In  the  group  of  large  apples  there  were  474  fruits  having 
cells  above  or  below  the. normal  number;  in  the  group  of  small  apples 
the  number  was  315,  but  large  apples  were  more  numerous  than  small 
and  the  ratio  of  abnormalities  was  practically  equal  for  the  two  groups. 

Varieties  High  in  Seed  Production 

Certain  of  our  varieties  exhibited  an  exceptionally  strong  tendency 
to  multiplication  of  seeds;  at  least  three  of  these,  Winter  Rambo, 
Rhenish  May,  and  Shockley,  are  perhaps  worthy  of  individual 
consideration. 

winter  rambo 

In  the  large  size-group  of  Winter  Rambo  were  four  apples,  each 
with  eight  cells  containing  plump  and  abortive  seeds,  as  follows :  10-6, 
16-3,  11-5,  and  12-4.  In  the  second  of  these  fruits  there  was  an 
addition  of  three  to  the  expected  number  of  ovules.  Irregularity  in 
number  of  ovules  appeared  to  be  characteristic  of  this  variety;  the 
range  was  from  the  normal  of  10  for  a  five-celled  fruit  to  24  for  a 
six-celled  fruit.  One  of  the  fruits  examined  had  six  cells  with  4  ovules 
in  each  cell,  19  of  which  developed  into  seeds.  Of  550  Winter  Rambo 
apples  of  large  size,  35,  or  more  than  6  percent,  had  each  seven  cells. 
These  apples  contained  565  ovules,  an  average  of  16.14.  The  expected 
total  of  ovules  in  35  seven-celled  apples  is  490 ;  hence  there  was  here 
an  excess  of  over  15  percent.  The  seeds  that  developed  numbered 
411 ;  this  represents  72.75  percent  of  the  ovules  present,  but  falls  a 
little  more  than  16  percent  below  the  full  complement  for  35  seven- 
celled  fruits.  The  lowest  seed  production  in  these  fruits  was  six  in 
one  fruit  having  14  ovules;  the  maximum  production  was  seventeen 
seeds  in  a  fruit  having  17  ovules.  The  maximum  seed  production  in 
this  variety  falls  to  two  six-celled  apples,  one  of  which  had  19  ovules, 
all  of  which  formed  good,  plump  seeds ;  the  other  had  24  ovules,  19  of 
which  became  fully  developed  seeds.    At  the  other  extreme  were  two 


192  Bulletin  No.  203  [August, 

fruits  with  three  seeds  each,  both  having  the  expected  number  of 
ovules,  one  fruit  five-celled,  the  other  six-celled. 

In  this  variety  there  were  considerable  differences  between  large 
fruits  and  small  fruits  in  number  and  distribution  of  seeds.  These 
differences  are  best  shown  by  a  direct  comparison  of  the  distribution 
percentages  presented  in  Table  3. 

Table  3. — Distribution  of  Seeds  in  Large  and  Small  Winter  Eambo  Apples 


Number 

of 

apples 

Distribution  of  se 

3ds 

Percentage 
above  normal 

Average 

Size-group 

Percentage     Percentage 
normal       ( below  normal 

seed 
content 

Large 

Small 

550 
500 

17.09 
13.80 

45.64 
72.00 

37.27 
14.20 

9.98 
8.30 

Note. — Normal  is  here  taken  to  be  ten  seeds  to  each  five-celled  fruit. 

The  large  fruits  exceeded  the  small  fruits  by  more  than  20  percent 
in  average  of  seeds  to  each  fruit  and  by  more  than  32  percent  in 
number  of  seeds  produced.  The  fruits  having  seeds  in  excess  of  the 
normal  were  nearly  three  times  as  numerous  in  the  group  of  large 
apples  as  in  the  group  of  small  apples,  while  of  the  apples  below 
normal  in  seed  production  the  small  apples  exceeded  the  large  by  about 
35  percent.  In  this  variety,  then,  it  is  evident  that  the  large  fruits 
were  greater  seed  producers  than  were  the  small  fruits. 

RHENISH   MAY 

The  second  of  the  three  varieties  showing  greatest  tendency  to  multi- 
plication of  seeds  was  Rhenish  May,  in  which  the  large  size-group  was 
represented  by  2,398  apples  and  the  small  size-group  by  1,009  apples. 
For  the  large  apples  the  average  seed  production  was  11.65  and  for 
the  small  apples  7.55.  Ten  percent  of  the  large  apples  contained 
ten  seeds  each  and  produced  9  percent  of  the  seed  total  for  large 
apples;  30  percent  had  numbers  of  seeds  below  ten  and  carried  19 
percent  of  the  total  number  of  seeds,  while  60  percent  of  the  fruits 
had  seeds  in  excess  of  ten  and  carried  72  percent  of  the  seeds.  In  the 
group  of  small  apples  the  percentage  of  fruits  having  the  normal  of 
ten  seeds  each  was  10,  the  same  as  for  the  large  apples,  and  they  had 
13.3  percent  of  the  seeds  borne  by  the  group.  The  percentage  of  fruits 
with  less  than  ten  seeds  was  very  much  greater  than  for  the  large 
fruits,  72.4  percent  as  against  30  percent  for  the  large  fruits,  and 
these  carried  58.1  percent  of  all  the  seeds.  Only  17.6  percent  of  this 
group  had  above  ten  seeds  each,  but  they  produced  28.6  percent  of  the 
total  number  of  seeds.  The  superiority  of  large  apples  as  compared 
with  small  apples  in  seed  production  was  as  well  defined  in  Rhenish 
May  as  in  Winter  Rambo.  In  Table  4  arc  presented  the  figures  for  seed 
distribution  in  Rhenish  May. 


1917] 


Seed  Production  in  Apples 


193 


Table  4. — Distribution  of  Seeds  in  Large  and  Small  Ehenish  May  Apples 


Number 

of 
apples 

Distribution  of  seeds 

Size- 

Normal 

Below  normal       Above  normal 

Average 

seed 
content 

groups 

j     Per- 
Percent   centage 
of  total 

Percent 

Per-    | 
centage  Percent 
of  total 

Per- 
centage 
of  total 

Large. . . 
Small.... 

2398 
1009 

10 
10 

9.0 
13.3 

30.0         19.0    i     60.0 
72.4    |     58.1    |     17.6 

72.0 
28.6 

11.65 

7.55 

SHOCKLEY 

The  third  of  the  three  varieties  standing  highest  in  seed  production 
was  Shockley.  The  multiplication  of  seeds  in  this  variety  was  so 
pronounced  that  it  was  really  in  a  class  by  itself.  As  with  other  varie- 
ties, the  fruits  were  divided  into  two  size-groups ;  each  group  contained 
177  apples.  There  were  no  departures  from  normal  in  number  of 
cells;  each  fruit  had  five.  Unlike  the  other  varieties  there  was,  in 
Shockley,  but  very  little  difference  in  seed  distribution  between  large 
apples  and  small  apples.  The  tendency  to  multiplication  was  about 
the  same  in  all  fruits,  and  appeared  as  a  well-established  varietal 
characteristic.  Averages  of  seeds  to  each  fruit  and  seed  distribution 
are  shown  in  Table  5. 


Table  5. — Distribution  of  Seeds  in  Large  and  Small  Shockley  Apples 


Size- 

Number 

of 
apples 

Distribution  of  seeds 

Average 

groups 

Normal         |    Below  normal     |   Above  ] 

lormal 
Percent 

seed 
content 

Number  Percent  |  Number  |  Percent  Number 

Large.  . . 
Small.... 

177 
177 

4 

7 

2.26 
3.96 

21 
19 

11.86 
10.73 

152 
151 

85.88        15.04 
85.31  |     14.59 

The  total  number  of  ovules  in  all  fruits  was  6,536,  an  average  of 
18.5  for  each  fruit.  As  between  the  two  size-groups,  the  large  apples 
had  3,298,  or  50.5  percent,  and  the  small  apples  3,238,  or  49.5  percent, 
a  nearly  equal  distribution.  Of  the  total  ovules  80.3  percent  developed 
into  seeds ;  and  here,  also,  the  division  between  large  and  small  fruits 
approximated  equality.  The  lowest  number  of  ovules  in  any  fruit 
was  10  in  one  small  fruit.  Three  large  fruits  and  one  small  fruit 
had  each  11  ovules,  and  two  large  and  five  small  had  each  12.  At 
the  other  extreme,  one  large  fruit  had  27  ovules,  21  of  which  developed 
into  seeds,  and  one  small  fruit  had  27  ovules,  all  of  which  became 
seeds.  Two  large  fruits  had  each  26  ovules :  one  of  these  developed 
24  seeds,  the  other  22.  Four  fruits  had  25  ovules  each  with  an  average 
of  21  seeds.  The  maximum  frequency  of  ovules  falls  on  20,  there 
being  thirty-one  large  apples  and  thirty-six  small  apples  having  each 


194  Bulletin  No.  203  [August, 

this  number.  These  apples  having  20  ovules  each  showed  wide  range 
in  seed  development.  Of  the  large  fruits,  one  had  1  seed,  one  had  2, 
and  one  had  5 ;  and  at  the  other  extreme,  three  developed  the  total  of 
20  each,  two  had  19  each,  and  five  had  18  each.  Among  the  small 
apples  having  20  ovules,  four  had  no  seeds;  one  had  11  seeds,  two  had 
13  each,  and  nine  had  the  full  complement  of  20  each.  Aside  from 
the  four  apples  just  referred  to  as  having  20  ovules  each  and  no 
developed  seeds,  were  two  others  in  the  same  group  that  were  seedless ; 
one  of  these  had  17  ovules,  the  other  15.  Some  of  the  ovules  in  these 
six  seedless  fruits  had  enlarged  the  integuments  somewhat,  but  none 
approached  the  size  of  mature  seeds  and  all  were  perfectly  flat,  with 
nothing  to  indicate  any  activity  in  the  direction  of  embryo  develop- 
ment. 

In  order  to  indicate  the  position  with  regard  to*  the  size  and  weight 
of  these  parthenocarpic  fruits  as  compared  with  other  apples  of  the 
same  group  that  stand  high  in  seed  production,  six  apples,  each  having 
twenty  ovules,  all  represented  by  apparently  perfect  seeds,  were  taken 
at  random  and  are  shown  in  comparison  with  six  seedless  fruits  in 
Table  6. 

Table  6. — Comparison  of  Seedless  Fruits  with  Fruits  of  High  Seed 
Production  as  to  Size  and  Weight:   Shockley 


Aver,  weight 
in  grams 

Aver,  diameter  (mm.) 

Long 

Transverse 

Six  seedless  fruits 

102.75 
94.49 

49 
51 

64 

Six  fruits  with  20  seeds  each 

58 

It  here  appears  that  the  parthenocarpic  fruits  were  not  the  smallest 
in  the  group,  as  they  exceeded  an  equal  number  of  fruits  that  were 
highly  productive  of  seeds,  both  in  weight  and  in  transverse  diameter. 
The  stimulus  of  the  assumed  pollination  developed  fruits  of  good 
size  in  the  absence  of  fertilization.  Fig.  1  shows  abnormal  seed  pro- 
duction in  Shockley. 

HUNTSMAN 

One  other  variety  may  be  referred  to  here,  the  Huntsman,  not  so 
much  because  of  its  high  seed  content,  altho  one  fruit  reached  a 
maximum  of  18  seeds,  but  because  of  the  symmetry  of  parts,  the  very 
open  character  of  the  core,  the  size  and  uniformity  of  cells,  and  the 
breadth  of  carpels.  The  variety  was  represented  by  731  large  fruits  and 
530  small.  The  average  seed  content  of  the  large  apples  was  7.97; 
of  the  small  apples,  6.66.  Over  11  percent  of  the  fruits  had  11  or 
more  seeds  each,  bringing  the  variety  to  fourth  place  on  the  list  in 
this  particular.     It  was  exceeded  by  Shockley,   Rhenish  May,  and 


1917] 


Seed  Production  in  Apples 


195 


Fig.  1. 


-Seed  Production  in  Shockley.    Portions  of  Fruits  Showing  Number 
and  Arrangement  of  Seeds  in  Various  Carpels 


"Winter  Rambo,  percentages  for  which  have  been  given.  The  one 
fruit  that  had  18  seeds  was  photographed  in  section  to  show  regularity 
of  cells  and  high  seed  content ;  there  were  six  cells,  each  with  3  plump 
seeds.  This  apple  weighed  156  grams,  and  measured  54  mm.  in 
longitudinal  diameter  and  72  mm.  in  transverse  diameter.  A  section 
of  the  fruit  appears  in  the  front  cover  illustration. 


Varieties  Low  in  Seed  Production 

Of  the  least  productive  varieties,  Collins  had  the  lowest  seed  content 
of    any  of  the  varieties    examined.     The  261  large  apples    had  an 


196  Bulletin  No.  203  [August, 

average  of  4.09  seeds ;  the  maximum  of  nine  was  reached  by  5  fruits, 
16  fruits  had  only  one  seed  each,  and  48  had  two  each;  three  were 
seedless.  The  150  small  apples  averaged  2.8  seeds;  this  was  the  lowest 
average  found  for  any  group.  Four  fruits  had  seven  seeds  each ;  this 
was  the  maximum  for  the  group.  Twenty- two  had  one  seed  each ;  40 
had  two  each,  and  12  fruits  were  seedless.  The  apples  of  this  small 
size-group  were  well  above  the  size  limit  for  No.  1  apples,  as  is  shown 
by  the  average  transverse  diameter  of  68  mm.  and  by  the  average 
weight,  134  grams. 

Next  above  Collins  in  seed  production  was  Minkler.  In  the  large 
size-group  of  this  variety  there  were  863  apples,  which  produced  3,694 
seeds,  an  average  of  4.28  to  each  fruit :  4  fruits  had  each  the  maximum 
of  ten  seeds,  55  had  one  seed  each,  99  had  two  seeds  each,  and  20 
were  without  seeds.  The  apples  of  this  group  had  an  average  trans- 
verse diameter  of  73.31  mm.,  and  the  average  weight  was  170.85  grams. 

The  small  size-group  numbered  only  54  apples  with  an  average 
of  3.65  seeds  to  each  apple :  two  fruits  had  eight  seeds  each,  the  max- 
imum for  the  group,  and  three  fruits  were  seedless. 

Seed  Production  in  the  Remaining  Varieties 

The  twenty-six  varieties  that  have  not  been  specifically  mentioned 
had  various  seed  averages.  In  fourteen  of  them  the  range  of  averages 
was  between  5  and  8  seeds  to  each  fruit  and  in  twelve  it  was  between 
8  and  11.  With  two  exceptions  the  groups  of  large  apples  had  dis- 
tinctively greater  seed  averages  than  the  groups  of  small  apples.  The 
two  exceptions  were  Shockley,  already  mentioned  in  detail,  in  whicli 
the  difference  in  size-groups  was  very  slight,  and  McMahon.  In  this 
latter  variety  the  number  of  apples  was  200  for  each  group.  The 
group  of  large  apples  had  an  average  of  7  seeds  to  each  fruit  and 
the  group  of  small  apples  an  average  of  7.75  seeds.  The  small  apples 
also  reached  a  higher  maximum:  two  fruits  had  14  seeds  each,  while 
only  one  fruit,  in  the  group  of  large  apples,  reached  a  maximum  of  13. 

Size  of  Fruit  in  Relation  to  the  Percentage  of  Ovules 
Developed  as  Seeds 

Another  method  of  determining  the  relative  seed  production  of 
large  apples  and  small  apples  is  by  comparing  the  number  of  developed 
seeds  in  each  of  the  two  groups  for  each  variety.  Records  obtained 
from  twenty-one  varieties  are  presented  in  Table  7,  showing  for  each 
size-group  the  number  of  apples,  the  number  of  cells,  the  normal 
ovule  content,  allowing  two  to  each  cell,  the  number  of  ovules  actually 
present,  the  excess  above  normal,  the  number  of  good  seeds,  the  aborted 
seeds,  and  the  percentage  of  ovules  actually  present  that  developed 
as  seeds. 


1917] 


Seed  Production  in  Apples 


197 


Table  7. — Ovule  Production  in  Orchard  Varieties 


Variola 


Num 

ber 

of 
apples!  ~~els 


Num- 
ber 
of 


Ovules 


car- 


Nor- 
mal 
num- 
ber 


Num- 
ber 
found 


Excess 


Num- 
ber 
devel- 
oped 


Num- 
ber 
un- 
devel- 
oped 


Large  Apples 


Bailey  Sweet 

Collins 

Crawford 

Fameuse 

Golden  Ball 

Hibernal 

Indian 

Isham 

Mammoth  Black  Twig. 

McClellan 

McMahon 

Osceola 

Polische  Jungf  rau .... 

Eome 

Shockley 

Tolman 

Wealthy 

Willow 

Winter  Rambo 

Wolf  River 

Wythe 


200 

1001 

2002 

261 

1303 

2606 

200 

989 

1978 

200 

1000 

2000 

200 

1002 

2004 

200 

1000 

2000 

200 

1000 

2000 

200 

1000 

2000 

200 

1001 

2002 

200 

999 

1998 

200 

998 

1996 

200 

1001 

2002 

200 

1002 

2004 

200 

1002 

2004 

177 

885 

1770 

200 

1004 

2008! 

513 

2566 

5132 

150 

788 

1576 

550 

2950 

5900 

200 

1001 

2002 

200 

1000 

2000 

2288 
2606 
2019 
2003 
2114 
2008 
2156 
2052 
2002 
2010 
2208 
2157 
2339 
2029! 
3298 
2034| 
5135, 
1595] 
6778 
2167 
2321 


Total j    4851 1  24492 :  48984|  53319 


286 

1846 

441 

1067 

1539 

41 

1294 

72t 

3 

1303 

70C 

110 

1888 

226 

8 

1192 

816 

156 

1430 

726 

52 

1180 

872 

.  ,  . 

1036 

966 

12 

1627 

383 

212 

1400 

808 

155 

1862 

295 

335 

2073 

266 

25 

1479 

550 

1528 

2665 

633 

26 

1628 

406 

3 

4260 

875 

19 

1235 

360 

878 

5488 

1290 

165 

1823 

344 

321 

1948 

373 

4335 

39724 

13595 

Small  Apples 


Bailey  Sweet 

Collins 

Crawford 

Fameuse 

Golden  Ball , 

Hibernal 

Indian 

Isham 

Mammoth  Black  Twig, 

McClellan 

McMahon 

Osceola 

Polische  Jungf  rau 

Rome , 

Shockley 

Tolman 

Wealthy 

Willow 

Winter  Rambo , 

Wolf  River ; 

Wythe 


199 

995 

1990 

150 

742 

1484 

200 

979 

1958 

200 

1000 

2000 

200 

1001 

2002 

200 

998 

1996 

200 

1000 

2000 

200 

1000 

2000 

200 

997 

1994 

•  200 

999 

1998 

200 

998 

1996 

200 

1000 

2000 

200 

1001 

2002 

200 

1000 

2000 

177 

885 

1770 

200 

1003 

2006 

500 

2498 

4996; 

200 

1026 

2052 

500 

2603 

5206 

200 

1000 

2000 

200 

999 

1998 

2117 
1484 
1979 
2002 
2066 
2011 
2020 
2026 
1994 
2004 
2295 
2014 
2149 

2009; 

3238! 
2006 
5002 
2113! 
5540| 
2150 
2166J 


Total 1  4726  |  23724J  47448|  50385[ 

Average. 


127 

1645 

472 

420 

1064 

21 

1051 

928 

2 

1036 

966 

64 

1794 

272 

15 

1148 

863 

20 

809 

1211 

26 

1066 

960 

724 

1270 

6 

1498 

506 

299 

1551 

744 

14 

1341 

673 

147 

1729 

420 

9 

1196 

813 

1468 

2584 

654 

1362 

644 

6 

3978 

1024 

61 

1558 

555 

334 

4148 

1392 

150 

1629 

521 

168 

1673 

493 

2937 

33940 

16445 

67.36J 


198  Bulletin  No.  203  [August, 

The  number  of  large  apples  was  4,851 ;  of  small  apples,  4,726. 
In  all  but  three  of  the  varieties  the  numbers  of  ovules  present  in  the 
groups  of  large  fruits  were  higher  than  in  the  groups  of  small  fruits. 
The  exceptions  to  the  rule  were:  Hibernal,  in  which  variety  the  200 
fruits  in  the  small  size-group  had  three  more  ovules  than  had  the 
200  apples  in  the  large  size-group,  a  difference  so  small  as  to  bring 
the  groups  practically  to  equality ;  MacMahon,  in  which  the  group  of 
small  apples  exceeded  the  large  in  total  number  of  ovules  by  eighty- 
seven  ;  and  Willow,  in  which,  taking  into  consideration  the  fact  that 
the  group  of  small  apples  exceeded  the  large  by  fifty  in  number  of 
fruits,  there  was  an  excess  of  thirteen  ovules  for  the  small  group.  Of 
those  varieties  in  which  large  apples  exceeded  small  apples  in  numbers 
of  ovules,  Fameuse  had  the  least  difference  and  Winter  Rambo  the 
greatest.  The  average  difference  for  all  varieties  approximated  one 
hundred. 

Some  varieties  exhibited  little  tendency  to  increase  in  number  of 
ovules  above  the  normal ;  others  had  the  tendency  strongly  marked. 
In  Collins  and  Mammoth  Black  Twig  there  was  no  excess  in  either 
size-group ;  in  Tolman  there  was  no  excess  in  the  small  size-group, 
but  an  excess  of  twenty-six  in  the  large  size-group.  All  others  had  some 
excess  in  both  groups,  ranging,  in  the  groups  of  large  apples,  from 
three  for  Fameuse  and  Wealthy  to  1,528  for  Shockley,  and  in  the 
groups  of  small  apples,  from  two  for  Fameuse  to  1,468  for  Shockley. 

The  percentages  of  ovules  found  present  that  were  followed  by 
plump  and  apparently  viable  seeds  are,  perhaps,  the  best  gage  of 
the  relative  seed-producing  capabilities  of  the  large  and  the  small 
apples.  Of  the  twenty-one  varieties  under  consideration,  all  but  one 
had  the  higher  percentages  of  seeds  developed  in  the  groups  of  large 
apples.  The  one  exception  was  McMahon,  which  had  63  percent  of 
the  ovules  developed  into  good  seeds  in  the  group  of  large  apples,  and 
68  percent  thus  developed  in  the  group  of  small  fruits.  Percentages 
for  the  list  of  varieties  other  than  McMahon  ranged,  for  the  groups 
of  large  apples,  from  41  percent  for  Collins  to  89  percent  for  Golden 
Ball.  Half  the  varieties  had  percentages  of  80  or  above ;  others  were 
somewhat  less,  but  the  average  for  the  twenty  varieties  was  75  percent. 
On  the  other  hand,  the  range  of  percentages  of  plump  seeds  for  the 
groups  of  small  apples  was  between  28  for  Collins  and  87  for 
Golden  Ball,  with  an  average  for  the  twenty  varieties  of  67.  In  some 
varieties  the  differences  between  groups  were  small,  as  for  example, 
Hibernal  with  a  percentage  of  59  for  large  apples  and  57  for  small,  or 
Shockley  with  81  percent  for  large  and  80  percent  for  small.  In  others 
the  differences  were  considerable,  as  in  Mammoth  Black  Twig  with  52 
percent  for  large  and  36  percent  for  small,  or  Indian  with  66  percent 
for  large  and  40  percent  for  small.  For  the  small  apples  of  the  twenty 
varieties  taken  together,  the  average  of  seeds  developed  was  67  percent 
of  the  possible  as  against  75  percent  for  the  large  apples. 


1917] 


Seed  Production  in  Apples 


199 


In  separating  large  apples  from  small  apples  for  the  groups  con- 
sidered above,  a  gap  of  5  mm.  was  left  between,  that  is  to  say,  the 
minimum  transverse  diameter  admitted  to  the  group  of  large  apples 
was  5  mm.  more  than  the  maximum  transverse  diameter  included  in 
the  group  of  small  apples.  To  test  the  effect  of  greater  size  difference 
between  groups,  the  100  largest  Winter  Rambo  apples  were  selected 
for  comparison  with  the  100  smallest  of  the  same  variety.  The  original 
groups  of  Winter  Rambo  numbered  550  large  and  500  small,  a  suf- 
ficient number  for  a  fair  test  of  extremes. 

These  selected  centenary  groups  ranged  in  transverse  diameters 
as  follows :  the  large  apples  from  a  minimum  of  72  mm.  to  a  maximum 
of  87  mm.,  with  an  average  of  75  mm. ;  the  small  apples  from  a  min- 
imum of  40  mm.  to  a  maximum  of  52  mm.,  with  an  average  of  48  mm. ; 
the  gap  between  groups  was  20  mm.,  and  the  averages  differed  by 
27  mm.    The  averages  for  the  groups  are  tabulated  below : 


Table  8. — Comparison  of  Centenary  Groups  of  Large  and  Small 
Winter  Rambo  Apples 


Size-group 

Aver. 

weight 

in  grams 

Average  diameter 
in  mm. 

Aver.  No. 
good  seeds 

Aver.  No*, 
undevel- 
oped ovules 

Percentage 
of  ovules 

Long 

Transverse 

forming 
seeds 

Large 

Small 

167                   59 
57                  39 

75 

48 

10.64 
6.49 

2.53 
3.24 

81 
67 

In  the  original  group  of  550  large  apples  the  average  seed  content 
was  9.98 ;  in  this  group  restricted  to  the  100  largest  it  was  10.64,  an 
increase  of  nearly  7  percent,  and  there  was  a  corresponding  increase 
in  the  number  of  ovules  that  did  not  develop.  The  percentage  of 
ovules  forming  seeds  was  the  same  in  both  groups. 

In  the  group  of  500  small  apples  the  average  seed  content  was  8.3. 
The  100  smallest  apples  of  this  group  had  a  seed  average  of  6.49, 
nearly  22  percent  less  than  that  of  the  full  group.  The  increase  in 
undeveloped  ovules  was  over  14  percent  and  the  decrease  in  per- 
centage of  seeds  formed  was  about  8  percent.  As  between  the  centenary 
groups,  the  percentages  of  ovules  developing  into  good  seeds  were 
81  for  the  large  apples  and  67  for  the  small  apples. 

This  comparison  between  the  extremes  in  size  found  in  apples  of 
one  variety  confirms  the  results  obtained  in  the  analysis  of  seed  pro- 
duction for  all  the  varieties  and  strengthens  the  evidence  which,  taken 
together,  appears  to  establish  the  fact  that  large  apples  develop  a 
considerably  larger  proportion  of  the  ovules  they  contain  than  do 
small  apples. 

In  Table  7  is  reported  the  ovule  production  of  twenty-one  varieties 
represented  by  9,577  apples  nearly  equally  divided  into  two  groups 


200  Bulletin  No.  203  [August, 

on  the  basis  of  size.  Examination  in  detail  of  the  ovule  and  seed 
content  of  these  apples  indicates  in  a  positive  way  that  large  apples 
are  superior  to  small  apples  in  seed  production.  The  large  apples 
contained  nearly  6  percent  more  ovules  than  did  the  small  apples, 
the  total  of  seeds  produced  was  17  percent  greater,  and  the  percentages 
of  ovules  developed  into  seeds  were,  with  the  one  exception  cited, 
higher  for  the  groups  of  large  apples  than  for  those  of  small  apples. 

SPECIES  OF  MALUS 

The  fruiting  forms  of  the  genus  Mains  included  in  the  record  of 
seed  production  number  twenty-five.  They  represent  seventeen  named 
species  and  six  classed  as  varieties,  besides  two,  the  Hyslop  and  Yellow 
Siberian  Crabs,  carried  under  their  common  names.  There  is  much 
confusion  in  the  nomenclature  of  the  species  of  the  genus  and  the 
taxonomic  rank  of  some  of  our  forms  is  uncertain,  and  cannot  be 
definitely  determined  until  a  complete  monograph  of  the  genus  is 
available.  Three  of  the  forms,  namely,  Mains  Ioensis,  the  wild  crab 
of  the  middle  west,  Malus  Soulardi,  the  Soulard  Crab,  and  Mains 
fusca,  the  Oregon  Crab,  are  native.  Malus  Arnoldiana  is  a  seedling 
of  Malus  floribunda  originated  at  the  Arnold  Arboretum  several  years 
ago.  Malus  prunifolia  var.  (856)  also  originated  at  the  Arnold 
Arboretum  from  seed  collected  in  Japan  in  1892  by  Dr.  C.  S.  Sargent. 
The  names  with  descriptions  of  these  two  have  not  yet  been  published, 
but  doubtless  will  be  in  the  near  future.  It  is  probable  that  one  or 
two  of  the  other  forms  are  seedlings  having  origin  in  this  country, 
but  with  these  definite  and  possible  exceptions  the  forms  in  the  list 
are  of  European  or  Asiatic  origin. 

The  fruits  of  each  species  or  variety  were  weighed  and  the  average 
weight  was  recorded.  Each  individual  was  measured  with  calipers 
for  longitudinal  and  transverse  diameters.  It  was  then  cut  trans- 
versely and  record  made  of  the  number  of  carpels  and  the  number 
and  distribution  of  developed  seeds  and  undeveloped  ovules.  The 
aggregate  of  fruits  examined  was  6,642,  varying  for  the  different 
lots  from  22  for  M.  fusca  to  1,200  for  M.  Ringo  sublobata.  M.  fusca 
had  small  representation  because  but  few  fruits  were  available;  all 
others  had  100  or  more  fruits.  The  average  weight  for  all  fruits  was 
9.96  grams ;  if  the  two  large  crabs,  Hyslop  and  Soulard,  are  eliminated, 
this  average  drops  to  7.46  grams.  Five  of  the  forms  had  fruits  which 
averaged  less  than  one  gram  in  weight,  and  four,  besides  the  two 
crabs  just  mentioned,  had  fruits  that  averaged  above  10  grams.  *As 
a  means  of  giving  a  right  impression  of  the  range  in  size  and  form 
and  the  relative  sizes  of  the  different  crabs,  a  single  fruit  of  each  of 
the  twenty-five  forms  is  shown,  natural  size,  in  Figs.  2  to  7,  inclusive. 

Table  9  gives  the  distribution  of  carpels,  the  seed  distribution,  and 
the  percentage  of  ovules  forming  good  seeds  for  each  of  the  twenty- 
five  crab-like  forms. 


1917] 


Seed  Production  in  Apples 


201 


202 


Bulletin  No.  203 


[August, 


co 


EH        . 

B  5 


^  g 
•♦ 'a 

W  g 
o  • 

O    W 

<*§ 

nil 

W 

£'& 

Eh 
J  < 
<1    ^ 

is 


1917] 


Seed  Production  in  Apples 


203 


204 


Bulletin  No.  203 


[August, 


1917] 


Seed  Production  in  Apples 


205 


Fig.  6. — Crabs,  Natural  Size.    Left  to  Eight:    Yellow  Siberian  Crab  (857), 
Malus  fastigiata  bifera,  Mains  Ioensis 


Fig.  7. — Crabs,  Natural  Size.    Left  to  Eight:  Malus  Arnoldiana,  Malus  fusca, 
Malus  floribunda,  Malus  Sargenti,  Malus  atrosanguinea,  Malus  Toringo  (19664) 


Number  and  Distribution  of  Carpels 

There  were  wide  differences  among  species  in  number  and  distribu- 
tion of  carpels ;  the  range  in  numbers  was  from  2  to  12.  The  minimum 
of  two  carpels  was  found  in  two  species,  M.  Arnoldiana  and  M.  Sar- 
genti. M.  Arnoldiana,  represented  by  100  fruits,  had  two  fruits  each 
with  two  carpels;  in  both,  the  ovules  were  as  expected,  two  in  each 
cell ;  one  developed  three  plump  seeds,  the  other  only  one.  M.  Sargenti, 
represented  by  223  fruits,  had  one  fruit  with  only  two  carpels,  con- 
taining four  ovules ;  one  good  seed  developed  in  each  carpel.    At  the 


206  Bulletin  No.  203  [August, 

other  extreme  M.  spectabilis  (No.  615)  had  one  fruit  with  twelve 
carpels  and  another  with  eleven.  In  these  two  cases  the  large  number 
of  carpels  was  due  to  the  appearance  of  a  second  whorl  of  carpels 
superposed  upon  the  normal  whorl.  The  fruit  having  twelve  carpels 
had  seven  in  the  basal  whorl  and  five  in  the  upper  whorl :  these  twelve 
carpels  contained  thirty-one  ovules,  ten  of  which  developed  into  plump 
seeds,  and  of  this  ten,  three  were  in  the  carpels  of  the  superposed 
whorl.  Nine  other  fruits  had  the  additional  whorl  represented  by 
one  or  two  carpels  and  these  carpels  all  contained  developed  seeds. 
The  remaining  89  fruits  of  this  species  had  carpels  distributed  as 
follows :  13  with  the  normal  of  five,  49  with  six  carpels  each,  22  with 
seven,  and  5  with  eight  each;  but  in  all  these  fruits  the  additional 
carpels  were  crowded  into  the  one  whorl. 

Those  fruits  possessing  the  secondary  whorl  of  carpels  gave  external 
evidence  of  its  presence  in  enlargements  which  appeared  as  protuber- 
ances projected  vertically  about  the  basin.  These  protuberances  coin- 
cided with  those  carpels  in  which  seeds  were  developed,  and  for  those 
cases  in  which  the  seed  development  was  distributed  around  the  whorl, 
the  calyx  appeared  as  the  bottom  of  a  deep,  irregular  basin,  while 
for  those  in  which  only  one  or  two  seeds,  in  close  proximity,  on  one 
side,  were  developed,  the  resulting  protuberance  gave  a  one-sided  fruit 
with  the  calyx  appearing  as  if  on  the  side  of  the  apple.  See  Central 
fruit  in  Fig.  5. 

Two  other  species  showed  a  strongly  developed  tendency  to  multi- 
plication of  carpels;  these  were  M.  Mains  flore  pleno  and  M.  Scliei- 
deckeri.  The  first  had  3  fruits  with  a  maximum  of  nine  carpels,  8 
fruits  with  eight  carpels  each,  21  with  seven  each,  49  with  six  each, 
and  only  19  with  the  normal  five  carpels.  The  second  had  a  maximum 
of  eight  carpels,  represented  by  one  fruit;  82  fruits  had  each  seven 
carpels,  and  309,  or  51.5  percent  of  the  total  of  600,  had  each  six 
carpels.  Two  hundred  and  six  fruits  had  each  the  normal  of  five 
carpels,  and  two  fruits  had  only  four  carpels  each.  The  range  for  the 
first  species  was  5  to  9,  for  the  second,  4  to  8. 

Considering  the  aggregate  of  6,642  fruits  representing  the  twenty- 
five  crab  forms,  it  appears  that  4,565  fruits,  or  68.73  percent,  had  each 
the  normal  five  carpels.  With  numbers  of  carpels  less  than  five  there 
were  1,483  fruits,  or  22.33  percent;  and  the  aggregate  of  fruits  with 
numbers  of  carpels  above  normal  was  594,  or  8.94  percent. 

The  two  crabs  with  fruits  of  large  size,  Hyslop  and  Soulard, 
exhibited  no  departures  from  the  normal  of  five  carpels.  All  other 
crabs  showed  variation  in  numbers  of  carpels:  twelve  varied  only  in 
the  direction  of  diminished  numbers,  four  only  in  the  direction  of 
increased  numbers,  and  seven  showed  variations  in  both  directions. 

The  species  bearing  very  small  fruits  tended  more  strongly  to 
reduction  in  numbers  of  carpels  than  did  the  species  having  larger 


Four 

Five 

271 

7 

68 
391 

1917]  Seed  Production  in  Apples  207 

fruits;  for  example,  compare  100  fruits  each  of  the  four  species 
M.  Toringo,  M.  Sargenti,  M.  floribunda,  and  M.  atrosanguinea,  whose 
fruits  averaged  less  than  one  gram  in  weight,  with  equal  numbers  of 
the  four  forms  M.  baccata  (red  fruit),  M.  baccata  (red  fruit,  late), 
M.  baccata  maxima,  and  M.  prunifolia  var.  (838),  whose  fruits  ranged 
in  average  weight  from  6.62  grams  to  9.63  grams.  The  distribution  of 
carpels  in  these  forms  of  Malus  was  as  follows : 

Number  of  Carpels 

Three  Four        Five  Six 

Small-fruited  species 61 

Larger-fruited  species 1 

For  the  small-fruited  species  83  percent  of  the  fruits  had  numbers 
of  carpels  less  than  five,  while  only  17  percent  had  the  normal  num- 
ber. For  the  larger-fruited  species  only  2  percent  of  the  fruits  had 
less  than  five,  97.75  percent  were  normal,  and  one  fruit,  or  %  °f  1 
percent,  had  one  more  than  the  normal  of  five. 

While  it  was  generally  the  case  in  this  crab  group  that  the  very 
small  fruits  showed  the  greatest  tendency  to  reduction  in  numbers 
of  carpels,  there  were  exceptions,  as  in  the  case  of  one  variety  of 
M.  prunifolia,  the  600  fruits  of  which  had  an  average  weight  of  10.64 
grams  and  in  which  506  fruits,  or  84.33  percent,  had  numbers  of  car- 
pels less  than  five. 

Seed  Production 

The  averages  of  seeds  contained  in  fruits  of  the  twenty-five  spe- 
cies and  varieties  of  Malus  included  in  the  list  ranged  from  1.32  for 
M.  fusca,  which  was  represented  by  only  22  fruits,  and  2.02  for 
M.  atrosanguinea,  represented  by  100  fruits,  to  7.8  for  M.  Malus  flore 
pleno.  For  all  forms  considered  together  the  aggregate  of  seeds  pro- 
duced was  28,050,  which  gives  an  average  of  4.22  seeds  to  each  fruit. 
The  range  shown  was  rather  wide,  and  the  general  average  decidedly 
lower  than  for  the  small  fruits  of  orchard  varieties.  In  distribution 
the  range  was  from  0  to  14.  There  were  94  parthenocarpic  fruits, 
representing  nine  of  the  species.  Seventy-eight,  or  nearly  83  per- 
cent of  these,  occurred  in  the  variety  sublobata  of  the  species  Bingo 
(19689)  ;  the  remaining  16  were  found  in  numbers  from  1  to  4  in 
eight  other  species.  Fruits  with  one  seed  each  numbered  574 ;  these 
were  distributed  among  nineteen  of  the  species  in  numbers  from  1 
for  M.  Ringo  and  M.  Sib  erica  frutico  coccinea  to  312  for  the  variety 
of  M.  Ringo,  which  is  so  productive  of  parthenocarpic  fruits.  With 
two  seeds  each  there  were  1,037  fruits,  with  three  seeds  each,  1,130 
fruits:  this  was  the  maximum  frequency.  Numbers  for  higher  seed 
content  decreased  moderately  at  first  and  then  more  rapidly  until  the 
maximum  of  fourteen  was  reached  by  one  fruit  of  M.  Malus  flore  pleno. 


208  Bulletin  No.  203  [August, 

This  species  had  2  fruits  with  thirteen  seeds  each,  6  with  twelve  seeds 
each,  and  4  with  eleven  each.  Four  other  species  had  one  fruit  each 
reaching  a  maximum  content  of  eleven  seeds.  With  ten  seeds  each, 
there  were  65  apples,  less  than  1  percent  of  the  total  number  of  fruits 
examined.  Eight  species  reached  their  maxima  at  ten  seeds,  and  only 
five  species  had  more  than  this  number. 

In  31.  fusca  the  highest  number  of  seeds  was  three  in  each  of  two 
fruits,  but  the  number  of  fruits  of  this  species  was  too  small  to 
warrant  the  assumption  that  this  maximum  is  normal.  Next  above 
31.  fusca  two  species,  M.  atrosanguinea  and  31.  floribunda,  had  the 
number  five  as  the  maximum  of  seeds  produced ;  each  was  represented 
by  100  fruits ;  the  former  had  one  fruit,  the  latter  three  fruits,  each 
of  which  had  five  seeds. 

As  with  seed  production  in  the  orchard  varieties,  some  of  these  crab 
forms  tended  to  concentrate  within  a  small  range,  as  between  1  and  5 
for  31.  atrosanguinea  and  31.  floribunda,  two  closely  related  species; 
some  tended  to  wider  range,  as  2  to  14  for  31.  Malus  flore  pleno,  or  0 
to  11  for  M.  baccata  (red  fruit)  and  31.  Bingo.  Some  of  the  species 
had  very  small  seeds,  and  in  some  the  seeds  were  nearly  as  large  as 
the  average  in  orchard  varieties.  The  size  and  shape  of  the  seeds  of 
the  twenty-five  crab-like  forms  are  shown  in  Fig.  8  (natural  size). 

Numbers  of  Ovules 

It  developed  in  examining  the  apples  here  considered  that  for  most 
species  the  normal  complement  of  two  ovules  to  the  carpel,  or  ten  for 
an  apple  with  five  carpels,  held  with  great  regularity.  In  twelve  of 
the  species  not  a  single  departure  in  either  direction  from  the  expected 
normal  was  found.  This  group  of  twelve  species  contained  2,947 
fruits  which  had  an  aggregate  of  13,557  carpels  and  exactly  double 
this  number  of  ovules;  each  carpel  had  its  full  complement  of  two, 
no  more  and  no  less.  Approximately  one-half  the  ovules  developed 
into  seeds  that  appeared  normal  and  viable;  the  seeds  numbered 
13,622,  representing  50.24  percent  of  the  contained  ovules.  The  un- 
developed ovules  numbered  13,492,  representing  49.76  percent  of  the 
total  number;  these  were  of  all  sizes,  some  so  small  as  to  require  a 
hand  lens  for  clear  determination,  others  with  integuments  developed 
to  nearly  full  size,  but  perfectly  flat  and  containing  no  embryos.  Nine 
other  species  had  ovules  in  excess  of  the  normal  in  numbers  ranging 
from  1  to  300.  The  total  of  ovules  above  normal  was  421  distributed 
in  158  fruits.  Of  this  number  300  were  found  in  fruits  of  31.  specta- 
bilis  and  81  in  fruits  of  31.  Malus  flore  pleno,  two  species  that  are 
abnormal  in  most  flower  and  fruit  characters.  Excluding  these  two 
species,  the  other  seven  species  of  this  group  had  an  excess  above 
normal  of  40  ovules  distributed  in  35  fruits. 

31.  spectabilis  far  exceeded  all  others  in  number  of  surplus  ovules. 
This  species  had  300,  or  71.25  percent,  of  the  total  surplus,  and  these 


1917] 


Seed  Production  in  Apples 


209 


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210  Bulletin  No.  203  [August, 

were  distributed  in  91  of  the  100  fruits  examined  in  numbers  vary- 
ing from  one  to  eleven. 

The  81  surplus  ovules  in  M.  Malus  flore  pleno  were  distributed  in 
32  fruits  in  numbers  ranging  from  one  to  six. 

The  maximum  number  of  ovules  was  25  in  a  fruit  of  M.  spectabilis 
having  seven  carpels :  four  of  the  carpels  contained  4  ovules  each  and 
three  carpels  had  3  each.  The  maximum  for  individual  carpels 
was  5  ovules;  this  number  was  found  in  several  cases  in  this  same 
species.  Where  4  or  5  ovules  are  present,  they  are  arranged  in  two 
ranks  along  the  placenta  at  the  inner  margin  of  the  carpel. 

In  the  four  remaining  species  departures  .from  the  normal  in  the 
direction  of  decrease  in  numbers  were  recorded.  These  shortages  were 
small ;  16  for  31.  Sclieideckeri,  6  for  M.  Malus  var.,  4  for  M.  Sargenti, 
and  2  for  M.  Ringo  sxiblobata.  This  is  a  total  of  28  below  the  expected 
total  of  22,724  ovules  for  2,244  apples  having  11,362  carpels. 

In  two  or  three  cases  the  two  ovules  of  a  single  carpel  were  sup- 
pressed, but  for  all  others  one  of  the  pair  was  absent  or  so  undeveloped 
that  its  presence  could  not  be  detected. 

The  rarity  of  suppression  of  ovules  is  most  clearly  brought  out  by 
comparing  the  number  recorded  as  suppressed  with  the  total  of  ovules 
present.  The  6,642  apples  of  all  species  contained  32,192  carpels,  and 
with  two  ovules  to  each  carpel,  64,384  would  be  the  expected  total  of 
ovules.  The  actual  number  recorded  as  present  was  64,777,  but  this 
included  421  ovules  in  excess  of  normal.  Deducting  this  number  leaves 
64,356,  which  number,  if  increased  by  28,  the  total  of  ovules  sup- 
pressed, will  equal  the  normal  for  the  fruits  considered.  For  the 
apples  examined,  approximately  one  ovule  in  2,300  was  suppressed; 
the  percentage  is  sufficiently  low  to  indicate  that  suppression  is  of, 
rare  occurrence. 

Comparison  of  Orchard  and  Crab-like  Varieties  in  Ovule  and 
Seed  Production 

In  neither  size-group  of  orchard  varieties  were  deficiencies  in 
ovule  production  recorded,  but  in  all  varieties,  except  Collins  and 
Mammoth  Black  Twig  in  both  size-groups  and  Tolman  in  the  small 
size-group,  ovules  were  in  excess  of  normal  in  numbers  ranging 
from  two  for  Fameuse  in  the  small  size-group  and  three  for  the  same 
variety  in  the  large  size-group,  to  1,528  for  Shockley  in  the  large 
size-group  and  1,468  for  the  same  variety  in  the  small  size-group. 
The  variety  ranking  next  to  Shockley  in  number  of  ovules  in  excess 
of  normal  was  "Winter  Rambo,  which  had  878  in  the  large  size-group 
and  334  in  the  small  size-group,  but  this  variety  had  more  than  three 
times  as  many  large  apples  and  nearly  three  times  as  many  small 
apples  as  had  Shockley,  so  that  while  there  were  8.6  surplus  ovules 
to  each  large  apple  in  Shockley,  there  were  only  1.6  surplus  ovules 


11 


=  *d 

Sens  th 

Nos  re 

bi- 

??  il. 

rd 


80 
80 


80  }) 

81  2d 

82-  es 

82 

li  *■ 

83;  >st 


1966' 
1964- 
83!  ed 


iy 

Of 


S5i 
1965: 


ne 
38 
841  es, 

19681  4.0 

84;  4Z 

19641  OV 

1964;  ies 

84<  ^ 

82<  tly 


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84* 

1966< 


ire 


N 

ive 
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ers 

ers 
md 
is, 
the 
ted 
ing 
jses 


Table  9.— Seed  Pbodoction  in  Cbab-uxe  Sph  ies  and  Vableties  of  Malds 


baccata,  red  fruit. 
baccata,  red  fruit, 
■  baccata  maxima  .  . 


Malta  prvnifolia  var  . 


I  Soulardi 

>  sp.  (f)  Hyslop  Crab. 
I  »(>.  (  ()  Yellow  Sibci  iai 
t  spcctabilis  No.  615.  . . 
I  Toringo 


iOB  Of  fruits  as  t 


I'l^ri'il. lit  ion  of  fruits  as  to  i 


SO    115 
9'    17 


-_  carpel.       No.     I  i 
14  found    |  t 


24;    11,      4 


2  332 
9  436 
308 

1608 


1002 

U74 

4  250 

1350 

675 

1  193 

1584 

Kill 

849 

86.SG 

■  I  I.;", 
33.02 


31.70 

ii.;./„; 
64.04 
33.52 

48.11 

43.30- 


Table  10. — Seed  Phodoction  in  Ha:-d-E'iillinated  Pbdits 


Orchard  variel 
Orchard  ' 
Crab-like 
Crablike 

„  .,  ,  l  Crabdike  forms 

Sclfed  J  0rciari  varieties „i£ 


Average 

n!)""' 

Distribution  of  carpels 

1  AnT  I 

fruit 

^i^rse" 

of  good 

2     |  3    |    4    |      5 

6   |    7 

8        ™eds  |0|1|2|3|4|5|6|7|8|9|10|11!12 

13  |  11      15 

li, 

83.42  46.34 
87.37       48.21 

7.82  ,  19.35 
18.42       25.31 

2.71  14.75 
60.37       39.78 

58.48 
58.99 
22.01 
29.33 
16.71 
53.11 

1               13 

6 

.    40  |  838 

5i    61 

1 

812 
839 
1492 

31 
12 

10 

9 
9 

2 

16 

4 

M      7.23    i      11      7  1    14 
■       7.45    \      4        8      15 
1  74         L'7     HIS    297 
J       5.69    |      3  :      8      21 
2.56    i      1  j    11 ,    14 
|        5.16    111 

26  1    58  1    75 
23 1    42      80 
249    264    217 
14      17;    24 
6       9       2 

116  126  152  136  87  J  16  7 
90  !  145    164  1  137    104      19  '     a 

191ilS4  164  137 1  64  l1  1  4 
30  |    36     25  |    IS  i      8  |      2  ,  [  1 

22'  i     ;  2. 

I       1       I 

4 

1917]  Seed  Production  in  Apples  211 

to  each  large  Winter  Rambo  apple.  For  the  small  apples  the  difference 
between  the  two  was  still  greater.  In  Shockley,  multiplication  of 
ovules  appeared  as  a  well-established  characteristic,  and  in  this  regard 
the  variety  is  comparable  with  M.  spectabilis  among  the  crabs.  With 
other  varieties  whose  fruits  have  surplus  ovules,  the  numbers  are 
scarcely  sufficient  to  suggest  an  established  tendency  towards  multi- 
plication, but  rather  that  their  appearance  is  more  or  less  casual. 
However,  comparison  of  the  records  for  the  twenty-one  orchard 
varieties  (Table  7)  with  those  for  the  twenty-five  crabs  (Table  9) 
indicates  clearly  that  production  of  ovules  in  excess  of  the  expected 
normal  is  of  much  more  common  occurrence  among  orchard  varieties 
than  it  is  among  the  crabs. 

The  relative  standing  of  orchard  varieties  and  the  wild  or  semi- 
wild  forms  of  Mains  in  the  matter  of  seed  production  is,  perhaps,  most 
clearly  shown  by  comparing  the  percentages  of  ovules,  actually 
present,  that  develop  into  seeds.  Thus,  the  4,851  large  fruits  of 
twenty-one  orchard  varieties  contained  53,319  ovules  and  developed 
39,724  seeds,  or  74.5  percent;  the  4,726  small  fruits  of  the  same 
varieties  contained  50,385  ovules  and  developed  33,940  seeds,  or  67.38 
percent;  or,  taking  the  aggregate  of  apples  from  orchard  varieties, 
the  percentage  of  seeds  that  developed  was  71.03,  while  for  the  6,642 
fruits  of  species  of  Mains  the  64,777  ovules  developed  28,050  seeds,  or 
43.3  percent.  These  percentages  of  aggregates,  53.3  percent  for  species 
of  Mains  and  71.03  percent  for  orchard  varieties,  show  fairly  well  the 
relative  seed-producing  capacity  of  the  two  groups  and  are  sufficiently 
separated  to  indicate  in  a  positive  way  that  orchard  varieties  are 
decidedly  superior  to  wild  species  in  seed  production. 

SEED  PRODUCTION  UNDER  CONTROLLED  POLLINATION 

All  fruits  thus  far  considered  in  relation  to  seed  production  have 
developed  from  flowers  open  to  pollination  by  natural  agencies.  That 
the  insect  agents  did  the  work  well  and  that  weather  agencies  were  not 
adverse  may  be  assumed  from  the  fairly  full  crops  borne  by  the  trees. 

The  question  as  to  whether  protection  of  flowers  and  the  artificial 
application  of  pollen  gives  equal  or  greater  seed  production  than  does 
open  pollination  is  naturally  suggested,  and  brief  mention  of  seed 
production  in  fruits  developed  from  protected  hand-pollinated  flowers 
may  be  made  here. 

The  fruits  resulting  from  hand  pollination  of  emasculated  flowers 
protected  by  paper  bags  numbered  4,504  for  the  six  seasons  1909  and 
1911-1915,  but  of  these  fruits  there  were  643  for  which  the  record  is, 
in  some  detail,  incomplete ;  these  are  omitted,  leaving  3,861  fruits,  the 
records  from  which  are  here  considered.  These  fruits  were  separated 
into  four  groups  according  to  parentage  for  the  purpose  of  maintaining 
a  distinction  between  and  recording  the  behavior  of  the  two  classes 


212  Bulletin  No.  203  [August, 

of  apples,  orchard  varieties  and  crab-like  species  of  Mains,  when 
crossed  in  different  ways.  At  this  time  it  is  not  the  purpose  to  con- 
sider these  combinations  further  than  to  show  carpel  and  seed  distri- 
bution and  seed  averages.  The  four  classes  of  crosses  were :  orchard 
varieties  X  orchard  varieties,  represented  by  833  fruits ;  orchard  varie- 
ties X  crab-like  forms  of  Mains,  represented  by  857  fruits;  crab-like 
forms  of  Mains  X  orchard  varieties,  represented  by  1,967  fruits ;  and 
crab-like  forms  of  Mains  X  crab-like  forms  of  Mains,  represented  by 
204  fruits.  To  these  may  be  added  45  fruits  resulting  from  self- 
pollinated  flowers  of  crab-like  forms  of  Mains  and  12  fruits  from 
selfed  flowers  of  orchard  varieties.  These  additional  classes  had  small 
representation  because  most  efforts  to  produce  self-fertilized  fruits 
have  failed  entirely.  It  is  general  thruout  the  genus  Mains  that 
stigmas  of  flowers  of  the  very  diverse  forms  do  not  readily  accept 
their  own  pollen,  and  this  characteristic  is  more  commonly  apparent 
among  orchard  varieties  than  it  is  among  the  less  highly  developed 
crab-like  forms.  As  hybridity  in  plants  tends  strongly  towards  ste- 
rility, the  prevalence  of  self -sterility  in  species  and  varieties  of  Mains 
indicates  the  probable  hybrid  nature  of  many  of  the  forms.  This, 
to  the  breeder,  is  a  discouraging  feature,  because  selfing  is  essential 
to  determining  the  transmission  and  segregation  of  particular  pa- 
rental characters. 

Records  of  carpel  distribution  with  number  and  distribution  of 
seeds  for  each  of  the  classes  of  fruits  resulting  from  controlled  pollina- 
tions are  brought  together  in  Table  10.  There  is  nothing  in  this 
table  to  indicate  marked  superiority  in  seed  production  of  fruits 
developed  from  flowers  artificially  pollinated  over  fruits  from  flowers 
open  to  natural  agencies  for  transfer  of  pollen.  In  the  groups  of 
naturally  pollinated  orchard  varieties  the  average  number  of  seeds 
to  each  fruit  was  for  large  fruits  8.27  and  for  small  fruits  7.21,  or  for 
the  two  sizes  combined,  7.85.  For  fruits  from  controlled  pollinations, 
the  833  fruits  of  orchard  varieties  pollinated  by  orchard  varieties 
had  an  average  of  7.23  seeds  to  each  fruit,  and  the  857  fruits  of 
orchard  varieties  pollinated  by  crab-like  species  had  an  average  of 
7.45  seeds  to  each  fruit ;  or,  combining  the  two  groups  in  which  orchard 
varieties  served  as  mother  plants,  the  seed  average  was  7.35.  These 
averages  do  not  indicate  that  control  of  pollination  exercised  any 
marked  influence  upon  seed  content.  Fruits  of  the  twenty-five  crab- 
like forms  of  Mains  developed  from  open-pollinated  flowers  had  an 
average  of  4.22  seeds  to  each  fruit.  The  204  fruits  of  crab-like  forms 
which  resulted  from  hand  pollinations  with  pollen  from  other  crab 
forms  had  an  average  of  5.69  seeds  to  each  fruit,  while  the  1,967  crab 
fruits  developed  from  flowers  hand  pollinated  with  pollen  of  orchard 
varieties  had  an  average  content  of  4.74  seeds  to  each  fruit ;  or,  com- 
bining these  groups  in  which  the  mother  plants  are  crabs,  the  average 
was  4.83  seeds  to  each  fruit.    Here  the  averages  for  fruits  from  con- 


1917]  Seed  Production  in  Apples  213 

trolled  pollinations  are  in  advance  of  those  for  fruits  from  open 
pollinations,  but  the  differences  are  not  great,  and  when  the  disparity 
in  numbers  of  fruits  averaged  in  the  different  groups  is  considered, 
it  appears  that  further  investigation  is  needed  before  a  stable  basis  for 
definite  conclusions  can  be  reached.  It  may  be  stated,  however,  that 
participation  in  the  making  and  compiling  of  such  records  as  we  now 
have,  together  with  study  of  the  data,  has  given  a  rather  definite  im- 
pression that  whether  the  pollination  is  open  or  controlled  makes  small 
difference  in  the  proportion  of  ovules  that  develop  as  viable  seeds. 

CONCLUSIONS 

1.  From  the  foregoing  study  of  seed  production  in  apples  it 
appears  that  the  average  number  of  seeds  to  each  fruit  is  almost 
twice  as  great  for  orchard  varieties  as  for  fruits  from  crab-like  forms 
of  Mains.  Dividing  fruits  of  orchard  varieties  into  two  groups  on 
the  basis  of  size,  it  further  appears  that  large  apples  exceed  small 
apples  in  seed  production,  altho  the  difference  is  not  nearly  so  great 
as  is  the  difference  in  seed  content  between  orchard  varieties  and  crab- 
like forms. 

2.  The  range  in  average  seed  production  as  exhibited  by  different 
varieties  is  wide  with  both  orchard  varieties  and  crab-like  forms. 

3.  Departures  from  the  normal  of  five  carpels  to  each  fruit  occur 
with  both  orchard  varieties  and  crab-like  forms,  but  are  much  more 
frequent  with  crabs  than  with  orchard  fruits. 

4.  There  are  wide  differences  among  individual  varieties  and 
species  in  seed-producing  capacity,  and  the  range  in  numbers  of  seeds 
in  individual  fruits  is  also  wide. 

5.  The  assumed  normal  of  ten  seeds  to  each  fruit  is  likely  to 
occur  in  a  small  percentage  of  orchard  fruits,  but  rarely  occurs  in 
crab-like  forms. 

6.  Capacity  to  produce  seeds  appears  as  a  varietal  characteristic. 

7.  Parthenocarpic  fruits  occur  in  orchard  varieties  and  in  species 
of  Mains,  but  not  in  very  great  numbers. 

8.  There  is  great  regularity  in  the  appearance  of  ovules  in  normal 
numbers,  that  is,  two  in  each  carpel.  Few  cases  of  suppression  of 
ovules  occur ;  numbers  in  excess  of  normal  are  more  common  among 
orchard  varieties  than  among  crabs. 

9.  Comparison  of  seed  production  in  fruits  developed  from  flowers 
open  to  pollination  by  insects  and  in  fruits  from  hand-pollinated 
flowers  brings  out  only  small  differences ;  apparently  seed  production 
is  not  dependent  upon  the  manner  in  which  pollination  is  effected. 

10.  Considerable  differences  appear  in  seed  production  of  indi- 
vidual fruits  and  of  particular  varieties,  but  averages  of  groups 
warrant  the  conclusion  that  the  more  highly  developed  orchard 
varieties  exceed  crabs  in  seed  production  and  that,  as  between  large 
and  small  fruits,  large  fruits  produce  the  greater  number  of  seeds. 


